Battery Wake-Up
First Claim
1. A method to fast detect a low voltage in the range of few μ
- Volts, comprising the following steps;
(1) providing a circuit comprising input ports for a voltage to be measured, an output port, a pre-amplifier, a buffer amplifier, an arrangement of switches used for calibration of the circuit, an integrator stage with reset function, and a voltage source for calibrating the integrator stage;
(2) calibrating the pre-amplifier before each measurement of the voltage is performed;
(3) start calibration of the integrator stage by providing a voltage stimulus from said voltage source to the integrator stage;
(4) storing the integrated output signal of the integrator stage generated from said calibration voltage measurement;
(5) setting said switches to perform the voltage measurement;
(6) storing the integrated output signal of the integrator stage generated from said voltage measurement; and
(7) generating an output signal of the circuit if a difference between the calibration signal and the measurement signal exceeds a defined level, wherein all errors of the circuit are eliminated by said differentially generated signal.
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Accused Products
Abstract
Circuits and methods for fast detection of a low voltage in the range of few μVolts have been achieved. In a preferred embodiment the low voltage represents a current via a shunt resistor and the circuit is used to generate a digital wake-up signal. In regard of the wake-up application the circuit invented is activated periodically and in case of a certain level of the voltage drop, e.g. 50 μV, at the shunt resistor. The time required for a measurement of the voltage drop is inclusive calibration and integration time far below 1 ms. It is obvious that the circuit invented can be used for any measurements of very small voltages.
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Citations
19 Claims
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1. A method to fast detect a low voltage in the range of few μ
- Volts, comprising the following steps;
(1) providing a circuit comprising input ports for a voltage to be measured, an output port, a pre-amplifier, a buffer amplifier, an arrangement of switches used for calibration of the circuit, an integrator stage with reset function, and a voltage source for calibrating the integrator stage; (2) calibrating the pre-amplifier before each measurement of the voltage is performed; (3) start calibration of the integrator stage by providing a voltage stimulus from said voltage source to the integrator stage; (4) storing the integrated output signal of the integrator stage generated from said calibration voltage measurement; (5) setting said switches to perform the voltage measurement; (6) storing the integrated output signal of the integrator stage generated from said voltage measurement; and (7) generating an output signal of the circuit if a difference between the calibration signal and the measurement signal exceeds a defined level, wherein all errors of the circuit are eliminated by said differentially generated signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
- Volts, comprising the following steps;
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12. A circuit for fast detection of a low voltage in the range of few μ
- Volts, comprising;
a shunt resistor, wherein an input current generates a voltage drop; a pre-amplifier stage, wherein a first input is connected to a second terminal of a first switching means and a second input is connected to a second terminal of the shunt resistor; said first switching means, wherein a first terminal of the switching means is connected to a first terminal of the shunt resistor; a second switching means being connected between both inputs of the pre-amplifier, wherein a first terminal of the switching means is connected to a first terminal of the shunt resistor; a first capacitor, wherein a first terminal is connected to the output of the preamplifier and a second output is connected to a first input of a buffer amplifier and to a first terminal of a third switching means; said third first switching means, wherein a second terminal is connected to a positive terminal of a first voltage source; said first voltage source, having a positive and a negative terminal, wherein a negative terminal is connected to ground; said buffer amplifier, having two inputs and an output, wherein a second input is connected to the output, and the output is further connected to an input of an integrator stage; said integrator stage comprising; an input resistor connected between the output of the buffer amplifier and a first input of an operational amplifier; said operational amplifier having two inputs and an output, wherein a second input is connected to the positive terminal of the first voltage source and the output is connected to an input of a sample and hold stage, to a second terminal of a feedback capacitor and to a second terminal of a reset switching means; said feedback capacitor wherein a first terminal of the feedback capacitor is connected to the first input of the operational amplifier; and said reset switching means wherein a first terminal of the reset switching means is connected to the first input of the operational amplifier; and said sample and hold stage generating a digital output signal of the circuit. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19)
- Volts, comprising;
Specification